Here is my 20 gallon tank with my current setup... i don't have dividers yet so I can't filter it, but they have water around their tanks and the heater is keeping them all nice and toasty. And I have garbage bag plastic stuck in a sheet protector to keep them from seeing each other so they won't all be going crazy...lol. I can't WAIT to get my plexiglass dividers and set it up!!